It is shown in Stargate that there is a limited number of chevrons in each gate. Since we need a chevron for the origin point at the end of each "dialup", it can not be more origin planets than chevrons (e.g. 39).

Since there are obviously more than 39 planets shown on the TV show, how could the series be so long? How could it last long enough long to even Atlantis and Universe?

EDIT: Note: this is not a duplicate of Is there any indicator as to how many planets have Stargates? because there an estimation of the number of stargates is requested, and here the question is about how could that number be so high when you need Point of Origin chevrons and there are not so many different PoO chevrons available.

It is not answered there, but thanks, it was an interesting reading. What I want to know is: if there are 39 possible signs in stargates, there could not be more than 39 origin planets. Am I right?
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EnviteAug 5 '14 at 7:47

1

@Envite - Each gate only has one unique symbol. All the others are standard across all gates. Think of the DHD as your cellphone keypad and the unique symbol as the green call button to initiate the call.
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Richard♦Aug 5 '14 at 8:12

3 Answers
3

Each gate contains 38 standard symbols as well as a single unique PoO symbol (Point of Origin). The 38 symbols are used as a way of addressing the gate with the 39th symbol acting as the final command to the stargate to begin the dialling sequence.

This means that each Stargate has 38 common chevrons and one different from all other gates.

As you can see, the standard DHD matches up with the standard gate. The unique symbol is the only one that's new (on both the DHD and the gate) and is the reason why the teams need a few seconds to work out how to dial home, despite knowing Earth's location.

The mapping system used is described in some detail in the stargate film (along with a helpful diagram)

DANIEL : ** And uh...to find a destination within any three
dimensional space, you need six points to determine the exact
location.

[Daniel draws a cube and places a dot in the center of each of the six
"sides" of the cube and then draws lines between them all to intersect
at a spot in the cube.]

WEST :You said you needed seven points.

DANIEL :Well, no, six for the destination. But to chart a course, you need a point of origin.

[He draws a point some distance from a cube and then a line to where
all the cube spots intersect.]

Wouldn't that seventh point also need a set of coordinates for itself. Also why would one need a set of 6 coordinates for a 3D system, 3 coordinates would suffice, wouldn't they?
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Kushtrim P.Aug 5 '14 at 7:45

6

@KushtrimP. - The diagram suggests that you need to locate each point, then draw connective lines between them. The destination gate is at the centre of that grid. And yes, I'm aware that that makes no sense.
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Richard♦Aug 5 '14 at 8:09

4

@KushtrimP. Planets move, presumably "center" is a simplification and you're really just defining the area in which the gate can be in. You can see the results of this when considering what happens when multiple gates are in the same basic area--one of them has to cut off the others. (Presumably the point of origin knows its own co-ordinates, because that's where it is. I don't know why it isn't implicit, but interface design is hard)
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PhoshiAug 5 '14 at 8:51

4

@Richard: To be perfectly honest, the whole chevrons on the gate don't make any sense either, since you don't need them for dialing. This is like having an old dial-operated phone with an attached number pad for dialing. So you'd enter the number on the keypad, which would cause the dialplate to rotate to establish the connection. Well, this sounds really technologically advanced and similar... Great, I'll never ever be able to watch Stargate again without having to think of that old dial sound knack knack knack... :D
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MarioAug 5 '14 at 8:52

3

@Holger The address keeps getting longer until you enter the point of origin "terminator"; such as 8 cheveron addresses to other galaxys. To be honest given how the "point of origin" thing doesn't make any sense I have always thought of it as each gate has a terminator cheveron but they are all different for purely artistic reasons (as in in-universe artistic reasons)
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user20310Aug 5 '14 at 9:49

From what I gather the are 39 symbols and 6 chevrons for most gate addresses (the maths stays the same for longer addresses ) as the 7th chevron is fixed.

This means that was have 39C 6 (mathematics for out of 39 choices pick 6 Combinations.

Mathematically, this is calculated by saying once we pick symbol one we have n-1 choices, after we pick symbol two, n-2 choices. This continues until we get n-k choices where we stop. Where k is our number of chevrons, and n is our number of symbols. We now have, n!/ (n-k)! , e.g 39*38*...*33 We also need to discard correction sets that are the same besides order, so we divide as well by k! which is the number of ways we can order a set a k items (following a similar logic as above)

This is of no help. Each of these stargates needs to be an origin point, and the question is how could that be done if there are no 3 millions of chevrons to be used as origin point in order to dial back to Earth.
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EnviteAug 5 '14 at 8:21

6

Except that the final symbol must be the point of origin symbol. This means that you're choosing from a mixture of 38, not 39 symbols. Your calculation should be 2,760,681 combinations.
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Richard♦Aug 5 '14 at 8:26

@Uriel_SVK Given Daniel's explanation of the coordinate system in the movie, some symbols can be swapped and still have the same destination (but not all of them, so combinations isn't correct even given that). That said, while it was never retconned and is still the official explanation of how the coordinates work, other dialogue does indicate permutations is correct
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IzkataAug 5 '14 at 11:57

I cannot post more than two links, so I have only linked to the most important things.

Short answer:

Most Stargates use a normal glyph as a Point of Origin – these are not unique. Some Stargates have a special Point of Origin – these are typically thought to be unique, but might act as the same missing glyph.

Long answer:

In a number of episodes, it can be seen that a normal glyph is used as the Point of Origin for a planet. Knowing Earth's address, the extra lit glyph on the DHDs in Shades of Grey, New Ground, and Memento must be the Point of Origin for the respective planet. You can see that Memento's Tagrea and New Ground's P2X-416 have the same Point of Origin glyph. Thus, there does not appear to be a problem with reusing Point of Origin glyphs, and logically cannot be given the number of Stargates in the Milky Way network.

However, this raises a different issue. If a planet's Point of Origin is a normal glyph, this would mean that any other planet that contains that glyph in their address would not be able to be dialed. This would imply that a single location would not be able to reach every Stargate in the galaxy, unless under special circumstances.

Related to this is the point that Milky Way Stargates have 39 glyphs on the inner track. However, Milky Way DHDs only have 38 glyphs. Thus, one glyph from the Stargate is always missing on the DHD. In the image of Abydos' DHD, the Aquila glyph is missing (most other planets' DHDs are missing this glyph as well). We often see that Earth's special glyph appears on the DHDs of planets that use a normal glyph as their Point of Origin, including in The Tok'ra, Part 1, Cure, Memento, and Demons. This could mean that the special glyph is completely unused on those planets, that it acts as the missing Aquila glyph only on those planets, or that it is not as special as first assumed and is in fact a normal glyph.

@Richard – Izkata beat me to it; Destiny's hardware address specifically requires the symbol used for Earth's Point of Origin. It is on the Icarus Base's DHD (kind of blurry, but you can just make it out).

Can you back this up with some pictures? Obviously it's a production error but it would still be interesting to see some evidence. It may even merit its own question...
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Richard♦Aug 6 '14 at 14:43

@Richard It was a plot point of the pilot episode of Stargate Universe, Earth's point of origin was on the Icarus stargate. And aside from that, I remember what Silence describes as well - I think it was around season 2 or 3 where they zoomed in so close to an off-world gate that only about 3 symbols were visible at once, and made a point to zoom in on Earth's point of origin on that gate as well.
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IzkataAug 6 '14 at 23:32

I have added more links to pictures now that I have the ability to do so.
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SilenceAug 7 '14 at 0:05